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  <title>返回指定算法/模式组合的初始向量大小</title>
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  <div id="layout-content"><div id="function.mcrypt-get-iv-size" class="refentry">
 <div class="refnamediv">
  <h1 class="refname">mcrypt_get_iv_size</h1>
  <p class="verinfo">(PHP 4 &gt;= 4.0.2, PHP 5, PHP 7 &lt; 7.2.0, PECL mcrypt &gt;= 1.0.0)</p><p class="refpurpose"><span class="refname">mcrypt_get_iv_size</span> &mdash; <span class="dc-title">返回指定算法/模式组合的初始向量大小</span></p>

 </div>
 <div id="function.mcrypt-get-iv-size-refsynopsisdiv">
  <div class="warning"><strong class="warning">Warning</strong><p class="simpara">This function has been
<em class="emphasis">DEPRECATED</em> as of PHP 7.1.0. Relying on this function
is highly discouraged.</p></div>
 </div>
 <div class="refsect1 description" id="refsect1-function.mcrypt-get-iv-size-description">
  <h3 class="title">说明</h3>
  <div class="methodsynopsis dc-description">
   <span class="methodname"><strong>mcrypt_get_iv_size</strong></span>
    ( <span class="methodparam"><span class="type">string</span> <code class="parameter">$cipher</code></span>
   , <span class="methodparam"><span class="type">string</span> <code class="parameter">$mode</code></span>
   ) : <span class="type">int</span></div>

  <p class="para rdfs-comment">
   获取由 <code class="parameter">cipher</code>/<code class="parameter">mode</code>
   参数指定的初始向量大小。
  </p>
  <p class="para">
   <span class="function"><a href="mcrypt_enc_get_iv_size.html" class="function">mcrypt_enc_get_iv_size()</a></span> 更加有用，
   因为它使用由 <span class="function"><a href="mcrypt_module_open.html" class="function">mcrypt_module_open()</a></span> 
   返回的资源作为参数。
  </p>
 </div>

 
 <div class="refsect1 parameters" id="refsect1-function.mcrypt-get-iv-size-parameters">
  <h3 class="title">参数</h3>
  <p class="para">
   <dl>

    
     <dt>
<code class="parameter">cipher</code></dt>

     <dd>

      <p class="para"><strong><code>MCRYPT_ciphername</code></strong> 常量中的一个，或者是字符串值的算法名称。</p>
     </dd>

    
    
     <dt>
<code class="parameter">mode</code></dt>

     <dd>

      <p class="para"><strong><code>MCRYPT_MODE_modename</code></strong> 常量中的一个，或以下字符串中的一个：&quot;ecb&quot;，&quot;cbc&quot;，&quot;cfb&quot;，&quot;ofb&quot;，&quot;nofb&quot; 和 &quot;stream&quot;。</p>
      <p class="para">
       由于 ECB 模式不使用初始向量，所以会忽略它。
       在加密和解密的过程中，
       你需要使用相同的初始向量（想象成：开始点）。
      </p>
     </dd>

    
   </dl>

  </p>
 </div>


 <div class="refsect1 returnvalues" id="refsect1-function.mcrypt-get-iv-size-returnvalues">
  <h3 class="title">返回值</h3>
  <p class="para">
   返回初始向量的大小，以字节为单位。
   如果发生错误，返回 <strong><code>FALSE</code></strong>。
   如果指定的算法/模式不需要初始向量，返回 0。
  </p>
 </div>


 <div class="refsect1 examples" id="refsect1-function.mcrypt-get-iv-size-examples">
  <h3 class="title">范例</h3>
  <p class="para">
   <div class="example" id="example-910">
    <p><strong>Example #1 <span class="function"><strong>mcrypt_get_iv_size()</strong></span> 例程</strong></p>
    <div class="example-contents">
<div class="phpcode"><pre><span style="color: #000000">
<span style="color: #0000BB">&lt;?php<br />&nbsp;&nbsp;&nbsp;&nbsp;</span><span style="color: #007700">echo&nbsp;</span><span style="color: #0000BB">mcrypt_get_iv_size</span><span style="color: #007700">(</span><span style="color: #0000BB">MCRYPT_CAST_256</span><span style="color: #007700">,&nbsp;</span><span style="color: #0000BB">MCRYPT_MODE_CFB</span><span style="color: #007700">)&nbsp;.&nbsp;</span><span style="color: #DD0000">"\n"</span><span style="color: #007700">;<br /><br />&nbsp;&nbsp;&nbsp;&nbsp;echo&nbsp;</span><span style="color: #0000BB">mcrypt_get_iv_size</span><span style="color: #007700">(</span><span style="color: #DD0000">'des'</span><span style="color: #007700">,&nbsp;</span><span style="color: #DD0000">'ecb'</span><span style="color: #007700">)&nbsp;.&nbsp;</span><span style="color: #DD0000">"\n"</span><span style="color: #007700">;<br /></span><span style="color: #0000BB">?&gt;</span>
</span>
</pre></div>
    </div>

   </div>
  </p>
 </div>


 <div class="refsect1 seealso" id="refsect1-function.mcrypt-get-iv-size-seealso">
  <h3 class="title">参见</h3>
  <p class="para">
   <ul class="simplelist">
    <li class="member"><span class="function"><a href="mcrypt_get_block_size.html" class="function" rel="rdfs-seeAlso">mcrypt_get_block_size()</a> - 获得加密算法的分组大小</span></li>
    <li class="member"><span class="function"><a href="mcrypt_enc_get_iv_size.html" class="function" rel="rdfs-seeAlso">mcrypt_enc_get_iv_size()</a> - 返回打开的算法的初始向量大小</span></li>
    <li class="member"><span class="function"><a href="mcrypt_create_iv.html" class="function" rel="rdfs-seeAlso">mcrypt_create_iv()</a> - 从随机源创建初始向量</span></li>
   </ul>
  </p>
 </div>


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